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Fuel relay switch and charging system

Started by PaulE, August 12, 2017, 04:19:16 PM

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PaulE

I have a 1990 FJ1200 CV3 California model that suddenly would not start.  When I turn on the key the fuel pump does not kick in. I checked the pump and it works fine off the bike. I thought it was the fuel pump relay switch that went bad. I used a multi-meter to check resistance at each of the six blades on the relay and got no reading from any of them.  According to what I could find on the internet my fuel pump relay switch should have 10 or so blades but mine has only six.  It looks like the relay from an '86-'87 FJ1200. So I bypassed the fuel pump and used gravity feed to get fuel to the carbs.  That part works fine.  It gets plenty of gas without the pump. It runs fine except that after riding for 10 minutes or so the battery is not strong enough to restart the bike. I put the multi-meter on the battery and with the engine running can get a reading of 14.2 volts DC.  When you rev the bike the battery goes from 12.6 volts up to 14.2.  If you don't rev the bike and just let it idle it slowly drops voltage down to around 11.7 and stabilizes there.  The charging system seems to work and is strong.  My question is: is the fuel pump relay switch (which I think is defective) a part of the charging system?  Could it somehow be draining the bike at a faster rate than the charging system can charge it? The charging system is working (over 14 volts at higher rpm) yet the bike's battery is not charged enough to restart the bike after a 15 minute ride.  Maybe, just coincidentally, it's time to replace the battery.  I will take it to have the battery checked. I have a Clymer's shop manual but it does not tell how to test a fuel pump relay switch.  Anyone have any ideas how to test the relay switch?  It is my 3rd FJ and I love these bikes.  Would like to get it back on the road.  Thanks in advance for your help.

TexasDave

I have a Clymer manual for the 84-93 models and it goes into great detail in diagnosing this problem in the fuel pump section. Testing voltage from the wiring harness disconnected from the fuel pump relay to see if you are getting good voltage from the igniter to the relay. The relay is powered from the igniter. It also tests the relay with it plugged in to see if the voltage is good and the relay is good. Unfortunately it could be either the igniter or the relay OR a bad connection between the two. Also this is a six pin relay. This also looks to be a two person job as one has to watch the voltmeter. Sorry I can't be more help.

Dave
A pistol is like a parachute, if you need one and don't have one you will never need one again.

PaulE

Thanks for the response.  I will check your list of possibilities.  I'll also go back and look at my Clymer manual. Electrical gremlins are the hardest to find.